Investigation through neutron experimentation and crystal field calculation into the connectivity of multiferroic DyMnO3 and antiferromagnetic R = [Dy, Tb, Nd, Ce]

Abstract

Multiferroic materials that have a unique coupling of magnetic and electronic degrees of freedom are possible candidates for the next generation of data storage and data transfer technology. For this thesis we performed inelastic neutron scattering on an oxygen isotopically substituted sample DyMnO3. This was done in order to better understand the structural and magnetic interaction in these materials, and in an attempt to improve the magnetic signal for better performance in applications.

A comparison between DyMnO3, and also multiferroic TbMnO3 to the isostructural antiferromagnetic series RVO3 R = [Tb, Ce, Dy, Nd] is carried out in order to better understand the complex correlations in the multiferroic materials. Inelastic neutron scattering experiments were performed on TbVO3, CeVO3 and DyMnO3 and results from previously performed experiments on DyVO3, NdVO3 and TbMnO3 were compared to the crystal field excitation calculations. Crystal field excitation calculations used the point charge ionic model, and were found to predict the experimental crystal field excitations, with a deviation of 0.5 meV. In TbVO3 and CeVO3 the interaction between the molecular field and the crystal field excitations is confirmed. Moreover, the point charge ionic model was found to accurately predict the properties of the crystal field excitations for the strongly correlated electron systems: RMnO3 multiferroics and the RVO3 antiferromagnetic vanadates.